mcs/class/corlib/System.Security.Cryptography/DSA.cs

   1 //
   2 // System.Security.Cryptography.DSA.cs class implementation
   3 //
   4 // Authors:
   5 //   Thomas Neidhart (tome@sbox.tugraz.at)
   6 //   Sebastien Pouliot (spouliot@motus.com)
   7 //
   8 // Portions (C) 2002 Motus Technologies Inc. (http://www.motus.com)
   9 //
  10
  11 using System;
  12 using System.Text;
  13 using System.Xml;
  14
  15 // References:
  16 // a.   FIPS PUB 186-2: Digital Signature Standard (DSS)
  17 //      http://csrc.nist.gov/publications/fips/fips186-2/fips186-2-change1.pdf
  18
  19 namespace System.Security.Cryptography
  20 {
  21         /// <summary>
  22         /// Abstract base class for all implementations of the DSA algorithm
  23         /// </summary>
  24         public abstract class DSA : AsymmetricAlgorithm
  25         {
  26                 internal DSA () {}
  27
  28                 public static new DSA Create ()
  29                 {
  30                         return Create ("System.Security.Cryptography.DSA");
  31                 }
  32
  33                 public static new DSA Create (string algName)
  34                 {
  35                         return (DSA) CryptoConfig.CreateFromName (algName);
  36                 }
  37
  38                 public abstract byte[] CreateSignature (byte[] rgbHash);
  39
  40                 public abstract DSAParameters ExportParameters (bool includePrivateParameters);
  41
  42                 protected void ZeroizePrivateKey (DSAParameters parameters)
  43                 {
  44                         if (parameters.X != null)
  45                                 Array.Clear (parameters.X, 0, parameters.X.Length);
  46                 }
  47
  48                 public override void FromXmlString (string xmlString)
  49                 {
  50                         if (xmlString == null)
  51                                 throw new ArgumentNullException ();
  52
  53                         DSAParameters dsaParams = new DSAParameters ();
  54                         try {
  55                                 XmlDocument xml = new XmlDocument ();
  56                                 xml.LoadXml (xmlString);
  57                                 dsaParams.P = GetElement (xml, "P");
  58                                 dsaParams.Q = GetElement (xml, "Q");
  59                                 dsaParams.G = GetElement (xml, "G");
  60                                 dsaParams.Y = GetElement (xml, "Y");
  61                                 dsaParams.J = GetElement (xml, "J");
  62                                 dsaParams.Seed = GetElement (xml, "Seed");
  63                                 byte[] counter = GetElement (xml, "PgenCounter");
  64                                 // else we may have an exception
  65                                 byte[] counter4b = new byte[4];
  66                                 Array.Copy (counter, 0, counter4b, 0, counter.Length);
  67                                 dsaParams.Counter = BitConverter.ToInt32 (counter4b, 0);
  68                                 dsaParams.X = GetElement (xml, "X");
  69                                 ImportParameters (dsaParams);
  70                         }
  71                         catch {
  72                                 ZeroizePrivateKey (dsaParams);
  73                                 throw;
  74                         }
  75                         finally {
  76                                 ZeroizePrivateKey (dsaParams);
  77                         }
  78                 }
  79
  80                 public abstract void ImportParameters (DSAParameters parameters);
  81
  82                 public override string ToXmlString (bool includePrivateParameters)
  83                 {
  84                         StringBuilder sb = new StringBuilder ();
  85                         DSAParameters dsaParams = ExportParameters (includePrivateParameters);
  86                         try {
  87                                 sb.Append ("<DSAKeyValue>");
  88
  89                                 sb.Append ("<P>");
  90                                 sb.Append (Convert.ToBase64String (dsaParams.P));
  91                                 sb.Append ("</P>");
  92
  93                                 sb.Append ("<Q>");
  94                                 sb.Append (Convert.ToBase64String (dsaParams.Q));
  95                                 sb.Append ("</Q>");
  96
  97                                 sb.Append ("<G>");
  98                                 sb.Append (Convert.ToBase64String (dsaParams.G));
  99                                 sb.Append ("</G>");
 100
 101                                 sb.Append ("<Y>");
 102                                 sb.Append (Convert.ToBase64String( dsaParams.Y));
 103                                 sb.Append( "</Y>");
 104
 105                                 sb.Append ("<J>");
 106                                 sb.Append (Convert.ToBase64String (dsaParams.J));
 107                                 sb.Append ("</J>");
 108
 109                                 sb.Append ("<Seed>");
 110                                 sb.Append (Convert.ToBase64String (dsaParams.Seed));
 111                                 sb.Append ("</Seed>");
 112
 113                                 sb.Append ("<PgenCounter>");
 114                                 // the number of bytes is important (no matter == 0x00)
 115                                 byte[] inArr = BitConverter.GetBytes (dsaParams.Counter);
 116                                 int l = inArr.Length;
 117                                 while (inArr[l-1] == 0x00)
 118                                         l--;
 119                                 byte[] c = new byte[l];
 120                                 Array.Copy (inArr, 0, c, 0, l);
 121                                 sb.Append (Convert.ToBase64String (c));
 122                                 sb.Append ("</PgenCounter>");
 123
 124                                 if (dsaParams.X != null) {
 125                                         sb.Append ("<X>");
 126                                         sb.Append (Convert.ToBase64String (dsaParams.X));
 127                                         sb.Append ("</X>");
 128                                 }
 129                                 else if (includePrivateParameters)
 130                                         throw new CryptographicException();
 131
 132                                 sb.Append ("</DSAKeyValue>");
 133                         }
 134                         catch {
 135                                 ZeroizePrivateKey (dsaParams);
 136                                 throw;
 137                         }
 138                         finally {
 139                                 ZeroizePrivateKey (dsaParams);
 140                         }
 141
 142                         return sb.ToString ();
 143                 }
 144
 145                 public abstract bool VerifySignature (byte[] rgbHash, byte[] rgbSignature);
 146
 147         } // DSA
 148
 149 } // System.Security.Cryptography